in natural history, a meteor generally defined frozen rain, but differing from it in that the hailstones are not formed of single pieces of ice, but of many little spherules agglutinated together. Neither are these spherules all of the same consistence; some of them being hard and solid like perfect ice; others soft, and mostly like snow hardened by a severe frost. Sometimes the hailstone hath a kind of core of this soft matter; but more frequently the core is solid and hard, while the outside is formed of a softer matter. Hailstones assume various figures, being sometimes round, at other times pyramidal, crenated, angular, thin, and flat, and sometimes stellated, with six radii like the small crystals of snow.
Natural historians furnish us with various accounts of surprising showers of hail, in which the hailstones were of extraordinary magnitude. Mazzaray, speaking of the war of Louis XII. in Italy, in the year 1512, relates, that there was for some time an horrible darkness, thicker than that of night; after which the clouds broke into thunder and lightning, and there fell a shower of hailstones, or rather (as he calls them) pebble-stones, which destroyed all the fish, birds, and beasts of the country.—It was attended with a strong smell of sulphur; and the stones were of a bluish colour, some of them weighing an hundred pounds. Hist. de France, Tom. II. p. 339.
At Lille in Flanders, in 1636, fell hailstones of a very large size; some of which contained in the middle a dark brown matter, which, thrown on the fire, gave a very great report. Phil. Trans. No. 203.
Dr. Halley and others also relate, that in Cheshire, Lancashire, &c. April 29, 1697, a thick black cloud, coming from Carnarvonshire, disposed the vapours to congeal in such a manner, that for about the breadth of two miles, which was the limit of the cloud, in its progress for the space of 60 miles, it did inconceivable damage; not only killing all sorts of fowls and other small animals, but splitting trees, knocking down horses and men, and even ploughing up the earth; so that the hailstones buried themselves under ground an inch or an inch and a half deep. The hailstones, many of which weighed five ounces, and some half a pound, and being five or six inches about, were of various figures; some round, others half round; some smooth, others embossed and crenated: the icy substance of them was very transparent and hard, but there was a snowy kernel in the middle of them.
In Hertfordshire, May 4, the same year, after a severe storm of thunder and lightning, a shower of hail succeeded, which far exceeded the former: some persons were killed by it, their bodies beat all black and blue; vast oaks were split, and fields of rye cut down as with a scythe. The stones measured from 13 to 14 inches about. Their figures were various, some oval, others picked, some flat. Philosoph. Trans. No. 229.
It is remarkable, that, so far as we know, hail is a meteor which never produces any beneficial effect. The rain and dew invigorate and give life to the whole vegetable tribe; the frost, by expanding the water contained in the earth, pulverizes and renders the soil fertile; snow covers and preserves the tender vegetables from being destroyed by too severe a frost. But hail does none of all these. In winter, it lies not sufficiently close to cover vegetables from the nipping frosts; and in spring and summer it not only has a chilling and blasting effect from its coldness, but often does great damage to the more tender plants by the weight of the stones, and in great hail-showers the damage done in this manner is prodigious.
Hail is one of the natural phenomena for which it is almost impossible to account in any satisfactory manner. It is certain, that on the tops of mountains hailstones, as well as drops of rain, are very small, and continually increase in bulk till they reach the lower grounds. It would seem, therefore, that during their passage through the air, they attract the condensed vapour which increases them in size. But here we are at a loss how they come to be solid hard bodies, and not always soft, and composed of many small stars like snow. The flakes of snow, no doubt, increase in size as they descend, as well as the drops of rain or hailstones; but why should the one be in soft crystals, and the other in large hard lumps, seeing both are produced from condensed vapour? Some modern philosophers ascribe the formation of hail to electricity. Signior Beccaria supposes hail to be formed in the higher regions of the air, where the cold is intense, and where the electric matter is very copious. In these circumstances, a great number of particles of water are brought near together, ther, where they are frozen, and in their descent collect other particles, so that the density of the substance of the hailstone grows less and less from the centre; this being formed first in the higher regions, and the surface being collected in the lower. Agreeable to this, it is observed, that, in mountains, hail-stones, as well as drops of rain, are very small, there being but little space through which they can fall and increase their bulk. Drops of rain and hail also agree in this, that the more intense the electricity that forms them, the larger they are. Motion is known to promote freezing, and to the rapid motion of the electrified clouds may produce that effect. A more intense electricity also, he thinks, unites the particles of hail more closely than the more moderate electricity does those of snow. In like manner we feel thunder-clouds more dense than those that merely bring rain; and the drops of rain are larger in proportion, though they fall not from so great a height.